Case IH 19005 – Engine Control Module (ECM) / Engine Control Unit (ECU): Timeout error of CAN-Transmit-Frame ECM to NH3 (ammonia) Sensor

The Engine Control Module (ECM) has lost Controller Area Network (CAN) communication with the NH3 (ammonia) sensor. The NH3 sensor is a critical component of the Selective Catalytic Reduction (SCR) emissions system, used to monitor ammonia slip in the exhaust.

• Tier 4b
• Magnum
• Steiger
• Quadtrac
• Puma
• Maxxum
• Optum
• Farmall
• Axial-Flow 5140
• Axial-Flow 6140
• Axial-Flow 7140
• Axial-Flow 7240
• Axial-Flow 8240
• Axial-Flow 9240
• Patriot 2240
• Patriot 3230
• Patriot 3330
• Case 580N
• Case 621G

1. 1

   Inspect the wiring harness and the 8-pin connector at the NH3 sensor for physical damage, moisture, corrosion, or pushed-out pins.

2. 2

   Verify that the NH3 sensor is receiving proper power and ground from the harness.

3. 3

   Test the CAN bus lines (CAN High and CAN Low) between the ECM and the NH3 sensor for continuity, open circuits, or shorts to ground/power.

4. 4

   Check the machine's battery and charging system voltage, as low system voltage can cause CAN modules to drop offline and trigger timeout errors.

5. 5

   Inspect the NH3 sensor and its integrated control box for physical damage or extreme heat exposure.

1. 1

   Turn off the ignition and disconnect the battery to prevent electrical spikes.

2. 2

   Locate the NH3 sensor on the exhaust system (typically mounted downstream of the SCR catalyst).

3. 3

   Disconnect the sensor's 8-pin connector. Clean any corrosion with electrical contact cleaner and ensure the pins are seated tightly.

4. 4

   Repair any damaged sections of the wiring harness if faults were found during the diagnostic continuity tests.

5. 5

   If the wiring, power, and ground are all within specification but the CAN timeout persists, the NH3 sensor assembly (or its control module) has failed internally and must be replaced.

6. 6

   Install the new NH3 sensor.

7. 7

   Reconnect the battery, clear the fault codes using the Electronic Service Tool (EST), and run the engine to ensure the code does not return.